If you want to avoid marketing calls, the "right" way to do it is to register the number with the Telephone Preference Service (TPS). They have a web site where you can check the number and register. Simple enough...
There are, however, a few problems. I am looking at this as the new number I recently obtained (my old home phone number from 20 years ago) got another junk call. I checked, and it is no in the TPS.
Now, this should be simple, but it is not.
The TPS web site does not just want the number, which is all they actually require to maintain the register, they also want:-
Name
Full postal address
Email address
Agreement to their privacy and cookie policy
Well, half way through the web site filling in a form, it is a tad late to ask for agreement to the cookie policy, but what if I do not wish to agree? I cannot register.
As for the privacy policy - it looks rather iffy to me. Again, what if I don't agree?
First part of the privacy policy that seemed odd was "You should be aware that if you subsequently give any personal information to another company, the uses to the Telephone Preference Service privacy policy will no longer apply." I am not trying to be thick here, but they seem to say that if I give any personal information (at all?) to another company (any company?), then their privacy policy no longer applies. Well, of course I have given some personal information to some other companies! My employer for a start, and, well, loads of companies. Does that really stop the TPS privacy policy applying. Maybe I am misreading it. Seems a pointless policy if it stops applying so easily.
The other issue is they can give my personal information to other parties. They do say the uses are limited to "suppression purposes or to incorporate onto suppression software". So if the software wants email and postal addresses, it can be incorporated in to that software. That is one valid use of the data. The suppression software does not have the restriction on use (note the "or" in that statement). The TPS can also use for "research and statistical analysis".
It seems to me a great way for my phone number and postal address and email address to leak, and be given to the unscrupulous companies involved in direct marketing. That could mean I am actually giving my data to the very people I do not want calling me. Saying "unscrupulous" may seem harsh, and is my opinion, but is an opinion based on the fact we even need laws on this matter in the first place, that I get junk calls to TPS listed numbers all the time, and that the ICO have fined companies, so I feel it is not an unfounded assertion, at least for some of them.
I have now contacted OFCOM to add the number, and advised that they are not to store email or postal addresses or disclose that to third parties. If they want to validate my request they can call the number! We'll see what they say.
Interestingly, OFCOM themselves were promoting (on twitter) a text based TPS listing saying "Calling all mobile users...text ‘TPS’ & your email address to 85095 to reduce #nuisancecalls http://ofcom.in/295yXjW" so again asking people to provide email address when not needed to maintain the register.
I believe one of the Data Protection principles is you don't collect data you don't need. As my requests on twitter went unanswered, I have asked OFCOM to tell us more (FoI request). We'll see what they say.